Quantification of methane emissions at abandoned gas wells in the Central North Sea
Quantification of methane emissions at abandoned gas wells in the Central North Sea
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DOI：
10.1016/j.marpetgeo.2015.07.030
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发表时间：
2015-12-01
影响因子：
4.2
通讯作者：
Wallmann, Klaus
中科院分区：
文献类型：
--
作者：
Vielstaedte, Lisa;Karstens, Jens;Wallmann, Klaus
由于广泛的油气勘探，北海有数千口废弃的油井；其中许多据信正在泄漏甲烷。然而，这种温室气体中有多少排放到水柱中并最终到达大气尚不清楚。在这里，我们调查了北海挪威部分三口水深81-93米的废弃油井，所有这些油井都显示天然气渗入海底。散发出的气体的同位素特征指向生物成因，因此指向钻井进入的气藏上方沉积覆盖层中的气穴。对渗漏气泡的视频分析和直接气体流量测量发现，初始气泡直径在3.2至7.4毫米之间，每口井的海底气体流量总量在每年1至19吨甲烷之间。据估计，这三口井每年的海底总排放量为24吨，与Tommeliten的自然渗漏率相似，这表明泄漏的废弃油井是进入北海海底水域的甲烷的重要来源。然而，气泡驱动的甲烷直接输送到大气中的作用被发现可以忽略不计(
As a result of extensive hydrocarbon exploration, the North Sea hosts several thousand abandoned wells; many believed to be leaking methane. However, how much of this greenhouse gas is emitted into the water column and ultimately reaches the atmosphere is not known. Here, we investigate three abandoned wells at 81-93 m water depth in the Norwegian sector of the North Sea, all of which show gas seepage into the bottom water. The isotopic signature of the emanating gas points towards a biogenic origin and hence to gas pockets in the sedimentary overburden above the gas reservoirs that the wells were drilled into. Video-analysis of the seeping gas bubbles and direct gas flow measurements resolved initial bubble sizes ranging between 3.2 and 7.4 mm in diameter with a total seabed gas flow between 1 and 19 tons of CH4 per year per well. Estimated total annual seabed emissions from all three wells of 24 tons are similar to the natural seepage rates at Tommeliten, suggesting that leaky abandoned wells represent a significant source of methane into North Sea bottom waters. However, the bubble-driven direct methane transport into the atmosphere was found to be negligible (